Elastic-fluid turbine



June 5, 1928. 1,672,126

F. HODGKINSON ELASTIC FLUID TURBINE Filed April 11, 1925 F. Hodqkinson IWITNES I QNVENTOR (i 1m.

w BY M ATTORNEY Patented June 5, 1928.

UNITED STATES" PATENT OFFICE.

FRANCIS HOIJGKINSON, OF SWARTHMORE, PENNSYLVANIA, ASSIGNOB TO WESTING-HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- Vania,

ELASTIC-FLUID TURBINE.

Application filed April 11, 1925 Serial No. 22,364.

My invention relates to elastic fluid turbines, more particularly to therotors thereof, and has for itsobject to provide a process for seasoningsaid rotors before being placed into 'service whereby they shall bemaintained in permanent dynamic balance.

Apparatus adapted to carry out my improved process is illustrated in theaccompanying drawing in which the single figure illustratesschematically, apparatus adapted to carry out my invention.

In the manufacture ofiela stic fluid tur-' bines, especially ofrelatively large turbines the slots or to a slight flow of material inthe rotor when, subjected to the high temperature and. stresses ofoperation so that the material thereof assumes different relativepositions from those when originally balanced.

In accordance with m invention, after the rotor is first dynamicallybalanced, I

gradually heat it to a predetermined temperature, preferably to somewhatabove its designed workin temperature, slowly rotating it during t llSpart of the process in order to secure an even distribution of heat. Ithen rotate the rotor at a speed somewhat above its designed operatingspeed and finally gradually and uniformly cool it while rotating at alesser speed. When this process has been carried out I have found thatthe metal of the rotor and the blades in the slots will have assumedtheir permanent set. If, in assuming this condition, the rotor hasbecome dynamically unbalanced, it may be again balanced and permanentlyremain in balance.

Referring now to the drawing I show, by way of example, a closed vessel10 mounted upon a suitable foundation 11. The vessel 10 may be providedwith removable heads, 12-12, and heads of different shapes provided toaccommodate rotors of different lengths. Associated with the vessel 10are two bearing pedestals l3 and 14 disposed at opposite ends of thevessel 10 so as to accommodate the shafts of rotors to be tested.

Within the vessel 10 I show a rotor 16 to which blades 17 have alreadybeen applied. The shaft 18 of the rotor 16 is mounted inthebearing-pedestals l3 and 14. At 19 I' show a relatively small turbineemployed to drive the rotor 16 during the seasoning process and which iscoupled to the shaft 18 of the rotor 16 by means of a flexible coupling21. At 22 I show a heating medium supply mains, such, for example, as asteam main,

leading through a super-heater 23 to the vessel 10. The super-heater 23is provided with heating means 24, such as an oil burner, the intensityof which may be readily varied. Steam admitted to the vessel 10 isexhausted through a conduit '26. Leading from the conduit 26 is a branchconduit 27 which is connected to a condenser 28. Valves 29 and 31 areprovided in the conduit 26 and branch conduit 27 respectively, so thatthe steam passing through the vessel 10 may be exhausted either directlyto the atmosphere or through the condenser 28, thereby creating a vacuumwithin the vessel 10. The vessel 10 is provided with glands 32 and 33 toprevent material leakage of fluid from or to 'the interior thereof. Avalve 34 is also provided in the steam main 22 so that when it isdesired to quickly evacuate the vessel 10, the valve 34 is closed andthe condenser 28 put in operation. Means should also be provided foradmitting air at atmospheric pressure, when desired, to the vessel 10.To this end I show pipes 36 and 37 leading to the interior of the vessel10.

In carrying out my process, I place the rotor 16 within the vessel 10,as previously described, and slowly rotate it by means of the turbine19. At the same time, I admit steam, which need be only at a pressureslightly above atmospheric, from the main about 700 F. About six hoursare consumed in this operation. At the'same time I malntain a constantflow of steam through the vessel 10. With the temperature of the steamat about 700 F., or somewhat above the designed normal workingtemperature, and a constant flow through the heater box I continueslowly rotating the rotor 16 for about six hours more. By this time thetemperature of the rotor has reached approximately the temperature ofthe steam. It should be understood however, that in stating approximateperiods of time I have in mind relatively large rotors which requlrethat period of time to acquire the temperatures mentioned. It will beobvious however, that the time required for carrying out th1s processwould be less with relatively smaller bodies and greater with relativelygreater bodies and that the periods of time mentioned are given only byway of example.

After the steps previously described have been carried out, I close OKthe valves 34 and 29 and open the valve 31, putting the condenser 28 inoperation. This quickly evacuates the vessel 10 so that the rotor 16 maynow be rotated by the turbine 19 at the expense of relativelylittle'power. The turbine 16 is then rotated at a speed somewhat aboveits designed normal operating speed. I have found that a 20% overspeedis suflicient to successfully carry out this process. With the rotor 16operating above its normal operating speed and at a temperature somewhatabove its designed normal operating temperature any fiow of materialwithin the rotor which might occur in operation occurs in this processand the material of the rotor assumes its permanent set. This part ofthe operation is continued for about twenty minutes when the speed ofthe rotor is reduced to the slow rotation employed in the earlier partof the Process. The condenser 28 is then cut out of operation, thevalves 29 and 34 are opened and. the fire extinguished from under thesuperheater 23. This again provides for a circulation of saturated steamthrough the vessel 10, which permits a gradual cooling of the rotor 16.This operation is continued for about six hours when the rotor will havecooled sufliciently so that the valves in the o enings 36 and 37 may beopened, permittmg air at atmospheric pressure to pass to the interior ofthe vessel 10 and out at the exhaust conduit 26. When air is beingadmitted to the vessel 10, the valve 34 is kept closed.

The rotor, is kept slowly rotating while being cooled by air being drawnin through I the openings 36 and 37 for a period of about six hours whenit will have cooled down to approximately the temperature of thesurrounding atmosphere. After this rocess has been carried out it mayagain be c ecked From the foregoing it will be apparent that I hayeinvented an improved process for seasoning rotatable bodies whereby theymay be placed in service and remain permanently in dynamic balance.

While I have shown my invention in but one form, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various other changes and modifications, without departing from thespirit thereof, and I desire, therefore, that only such limitationsshall be placed thereupon as are imposed by the prior art or as arespecifically set forth in the appended claims.

What I claim is -1. The process of seasoning a rotatable body comprisingrotating the body and simultaneously heating it to a predeterminedtemperature approximately as high as its designed working temperature,subjecting it to stresses incident to service operation, and thengradually and uniformly cooling it.

. 2. The process of seasoning rotatable body comprising rotating the.body at a speed below its designed normal operating speed andsimultaneously gradually heating it to a predetermined temperatureapproximately as high as its designed working temperature, increasingthe rotational speed to above its designe operatin speed, and graduallyand uniformly cooling it.

3. The process of seasoning a turbine rotor comprising rotating therotor within a within a closed vessel and simultaneously subjecting itto an atmosphere of fluid at a.

predetermined temperature approximately as high as its designedtemperature until the rotor acquires a temperature approximating that ofthe fluid, rotatin it at a speed somewhat above its designed normaloperating speed, and slowly; rotating it and circulating through thevessel a heat absorbing medium until the rotor is cooled.

5. The process of seasoning a turbine rotor comprisin placing the rotorvin a closed vessel an rotating it slowly and at the same timecirculating throu h the vessel steam superheated somewhat a ove thedesigned normal temperature of motive fluid at admission until the rotoracquires a temperature approximating that of the superheated steam,evacuating the vessel and r0- tating the rotor at a speed slightly aboveits designed normal operating speed for about twenty minutes, slowlyrotating the rotor in an atmosphere of saturated steam, and circulatingair at atmospheric pressure through the vessel and at the same timeslowly rotating the rotor until cooled.

6. The method of seasoning a turbine rotor comprisin placing the rotor'in a closed vessel an slowly rotating it inan atmosphere of steamsuperheated to approximately 700 F. until the rotor acquires atemperature approximating that of the steam, evacuatin the vessel androtating the rotor at approximately 20% overspeed for about twentyminutes, reducing the speed of the rotor and circulating saturated steamthrough the vessel until the rotor is partially cooled and thencirculating air at atmospheric pressure and temperature until the rotoris finallycooled. 1 y

In testimony whereof, I have hereunto subscribed my name this third dayof April 1925.

FRANCIS HODGKINSON.

